Apparatus for counting microparticles using a gas reservoir to increase stability of air pressure

TECHNICAL FIELD

p-0002Embodiments of the present invention relate to apparatuses for counting microparticles

BACKGROUND

p-0003Dust particles can damage electronic items, such as magnetic disk drives or semi-conductors. For example, with the currently extremely narrow fly height requirements, even the smallest of particles can cause damage to a disk. Electronic items, such as these, are manufactured in a clean room to prevent and reduce the amount of dust particles that the electronic items are exposed to.

p-0004Therefore, during the process of manufacturing an electronic item, a microparticle measurement apparatus can be used to determine the amount of dust particles inside the clean room or on the surface of the electronic item. Gas can pass through the microparticle measurement apparatus to collect and count dust particles in order to estimate the amount of dust particles that have adhered to the electronic item as a part of quality control measurements. Action can be taken to reduce the amount of dust particles if the quality control measurements indicate that the amount of dust particles is above an acceptable threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0005The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention:

p-0006<figref idrefs="DRAWINGS">FIG. 1</figref> depicts a block diagram of a conventional negative-pressure microparticle measurement apparatus.

p-0007<figref idrefs="DRAWINGS">FIG. 2</figref> depicts a nozzle, according to one embodiment.

p-0008<figref idrefs="DRAWINGS">FIG. 3</figref> depicts a block diagram of microparticle measurement apparatus, according to one embodiment.

p-0009<figref idrefs="DRAWINGS">FIG. 4</figref> depicts a block diagram of a microparticle measurement apparatus, according to one embodiment.

p-0010<figref idrefs="DRAWINGS">FIG. 5</figref> depicts a block diagram of a microparticle measurement apparatus, according to one embodiment.

p-0011<figref idrefs="DRAWINGS">FIG. 6</figref> depicts a block diagram of a microparticle measurement apparatus, according to one embodiment.

p-0012<figref idrefs="DRAWINGS">FIGS. 7-9</figref> depict gas reservoirs, according to various embodiments.

p-0013The drawings referred to in this description should not be understood as being drawn to scale except if specifically noted.

DETAILED DESCRIPTION

p-0014<figref idrefs="DRAWINGS">FIG. 1</figref> depicts a block diagram of a conventional negative-pressure microparticle measurement apparatus <b>100</b>. The conventional negative-pressure microparticle measurement apparatus <b>100</b> includes a microparticle counter <b>110</b>, a vacuum pump <b>120</b>, a first gas pathway portion <b>130</b><i>a </i>at the gas inlet side <b>140</b><i>a</i>, a second gas pathway portion <b>130</b><i>b </i>between the microparticle counter <b>110</b> and vacuum pump <b>120</b>, and a third gas pathway portion <b>130</b><i>c </i>at the gas outlet side <b>140</b><i>b</i>. One or more tubes, among other things, can be used as a part of implementing a gas pathway portion. End <b>150</b><i>b </i>of the first gas pathway portion <b>130</b><i>a </i>is connected air tightly to the microparticle counter <b>110</b>.

p-0015Although a gas pathway portion may appear to go through the wall of a component, a gas pathway portion may be implemented, for example, using two tubes that are coupled on each side of that component's wall.

p-0016A nozzle <b>200</b>, as depicted in <figref idrefs="DRAWINGS">FIG. 2</figref>, may be attached to the other end <b>150</b><i>a </i>of the first gas pathway portion <b>130</b><i>a</i>. For example, the nozzle's end <b>210</b> can be connected to the first gas pathway portion's end <b>150</b><i>a</i>. Typically, the attachment of these respective ends <b>150</b><i>a</i>, <b>210</b> is air tight.

p-0017In measuring the amount of dust particles on the surface of an electronic item, the tip of the nozzle <b>200</b> is brought into proximity of the electronic item's surface. Normally, there is a gap between the electronic item's surface and the nozzle <b>200</b>'s tip <b>220</b>. If the nozzle <b>200</b>'s tip <b>220</b> is too far from the electronic item's surface, the measurement that is take will not be a measurement of the item's surface but instead includes a measurement of the gas, such as air, in the clean room, thus, producing an inaccurate measurement.

p-0018On the other hand, if the nozzle <b>200</b>'s tip <b>220</b> is brought too close to the electronic item's surface, the gap becomes too narrow, restricting the nozzle <b>200</b>'s opening <b>230</b>, which causes gas resistance to increase inside of the microparticle counter <b>110</b> and fluctuations in the air pressure and the air flow rate. The fluctuations in the air pressure and air flow rate may be extreme if the nozzle <b>200</b>'s tip <b>220</b> is very close to the electronic item's surface. The fluctuations in the air pressure and the air flow rate result in inaccurate dust particle measurements. Further, the life span of the conventional negative-pressure microparticle measurement apparatus <b>100</b> may be reduced by the fluctuations.

p-0019Differences in the shape of the nozzle <b>200</b>'s tip <b>220</b> can increase the differences in how different technicians perform measurements, further, increasing the difference in the size of the gap between the nozzle <b>200</b>'s tip <b>220</b> and the electronic item's surface from one measurement to another measurement. For example, different technicians may hold the nozzle <b>200</b>'s tip <b>220</b> close or further away from an electronic item's surface or may orient the nozzle <b>200</b>'s tip <b>220</b> different with respect to an electronic item's surface.

p-0020According to one embodiment, a negative-pressure-type microparticle measurement apparatus is provided that stabilizes air pressure at the location of the microparticle counter, even when there are fluctuations in the air flow rate supplied from the nozzle <b>200</b>. According to one embodiment, increasing the stability of the air pressure and air flow rate makes it easier to more accurately count the number of dust particles in a volume of gas received by the apparatus' microparticle counter.

p-0021<figref idrefs="DRAWINGS">FIG. 3</figref> depicts a block diagram of microparticle measurement apparatus <b>300</b>, according to one embodiment. As depicted in <figref idrefs="DRAWINGS">FIG. 3</figref>, the microparticle measurement apparatus <b>300</b> includes a microparticle counter <b>310</b>, a gas reservoir <b>350</b>, a vacuum pump <b>320</b> and apparatus <b>360</b>. The microparticle counter <b>310</b>, the gas reservoir <b>350</b>, and the vacuum pump <b>320</b> are inside of the apparatus <b>360</b>.

p-0022The first, second, third, and fourth gas pathway portion <b>330</b><i>ds </i>are a part of a gas pathway of the apparatus <b>300</b>. One end of a first gas pathway portion <b>330</b><i>a </i>is connected to the apparatus <b>300</b>'s enclosure <b>360</b> at the inlet side <b>340</b><i>a</i>, the other end of the first gas pathway portion <b>330</b><i>a </i>is connected to a microparticle counter <b>310</b>. One end of a second gas pathway potion is connected to the microparticle counter <b>310</b> and the other end of the second gas pathway portion <b>330</b><i>b </i>is connected to the gas reservoir <b>350</b>. One end of a third gas pathway portion <b>330</b><i>c </i>is connected to the gas reservoir <b>350</b> and the other end of the third gas pathway portion <b>330</b><i>c </i>is connected to the vacuum pump <b>320</b>. One end of a fourth gas pathway portion <b>330</b><i>d </i>is connected to the vacuum pump <b>320</b> and the other end of the fourth gas pathway portion <b>330</b><i>d </i>is connected to the apparatus <b>300</b>'s enclosure <b>360</b> at the outlet side <b>340</b><i>b. </i>

p-0023The vacuum pump <b>320</b> causes a volume of gas, such as air, to flow through the apparatus <b>300</b> by creating negative pressure. For example, the negative pressure caused by the vacuum pump <b>320</b> causes the volume of gas to be sucked into a nozzle's tip, pass through the first gas pathway portion <b>330</b><i>a </i>at the inlet side <b>340</b><i>a </i>to the microparticle counter <b>310</b>, through the second gas pathway portion <b>330</b><i>b </i>to the gas reservoir <b>350</b>, through the vacuum pump <b>320</b>, through the third gas pathway portion <b>330</b><i>c </i>and out the apparatus <b>300</b> at the outlet side <b>340</b><i>b</i>. The gas reservoir <b>350</b>, according to one embodiment, is inside the apparatus <b>300</b>'s enclosure <b>360</b>. According to one embodiment, the gas reservoir <b>350</b> is between the microparticle counter <b>310</b> and the vacuum pump <b>320</b>. The gas reservoir <b>350</b>, according to one embodiment, increases the stability of air pressure at the microparticle counter <b>310</b> even when air pressure or air flow rate provided by a nozzle coupled to the microparticle measurement apparatus <b>300</b> is unstable.

p-0024Although a gas pathway portion may appear to go through the wall of a component, a gas pathway portion may be implemented, for example, using two tubes that are coupled on each side of that component's wall.

p-0025<figref idrefs="DRAWINGS">FIG. 4</figref> depicts a block diagram of a microparticle measurement apparatus <b>400</b>, according to one embodiment. As depicted in <figref idrefs="DRAWINGS">FIG. 4</figref>, the apparatus <b>400</b> includes a microparticle counter <b>410</b>, a gas reservoir <b>450</b>, a vacuum pump <b>420</b>, and enclosure <b>460</b>. The microparticle counter <b>410</b>, the gas reservoir <b>450</b>, and the vacuum pump <b>420</b> are inside of the enclosure <b>460</b>. The gas reservoir <b>450</b> as depicted in <figref idrefs="DRAWINGS">FIG. 4</figref> is inside of the microparticle counter <b>410</b>.

p-0026The first, second, third, and fourth gas pathway portions <b>430</b> are a part of a gas pathway of the apparatus <b>400</b>. One end of the first gas pathway portion <b>430</b><i>a</i>, located at the apparatus <b>400</b>'s inlet side <b>440</b><i>a</i>, is connected to the apparatus <b>400</b>'s enclosure <b>460</b>, goes through the wall of the microparticle counter <b>410</b> and is connected to the gas reservoir <b>450</b>. One end of the second gas pathway portion <b>430</b><i>b </i>is connected to the gas reservoir <b>450</b> and the other end is not connected to any component and is inside of the microparticle counter <b>410</b>. One end of the third gas pathway portion <b>430</b><i>c </i>is not connected to any component and is inside of the microparticle counter <b>410</b>. The other end of the third gas pathway portion <b>430</b><i>c </i>goes through the wall of the microparticle counter <b>410</b> and is connected to the vacuum pump <b>420</b>. One end of the fourth gas pathway portion <b>430</b><i>d </i>is connected to the vacuum pump <b>420</b> and is connected to the apparatus <b>400</b>'s enclosure <b>460</b> at the inlet side <b>440</b><i>b. </i>

p-0027According to one embodiment, the gas reservoir <b>450</b> is at least partially air tight. According to one embodiment, the portion <b>470</b> of the apparatus <b>400</b> that is inside of the apparatus <b>400</b>'s enclosure <b>460</b> but outside of the microparticle counter <b>410</b> and vacuum pump <b>420</b> is not air tight. As depicted in <figref idrefs="DRAWINGS">FIG. 4</figref>, the second gas pathway portion <b>430</b><i>b </i>and the third gas pathway portion <b>430</b><i>c </i>are not connected to each other. For example, each of the second and third gas pathway portion <b>430</b><i>cs </i>has a respective end inside of the gas reservoir <b>450</b> and not connected to any component.

p-0028<figref idrefs="DRAWINGS">FIG. 5</figref> depicts a block diagram of a microparticle measurement apparatus <b>500</b>, according to one embodiment. As depicted in <figref idrefs="DRAWINGS">FIG. 5</figref>, the apparatus <b>500</b> includes a microparticle counter <b>510</b> and a gas reservoir <b>550</b> and enclosure <b>560</b>. The microparticle counter <b>510</b>, the gas reservoir <b>550</b>, and the vacuum pump <b>520</b> are inside of the enclosure <b>560</b>. As depicted in <figref idrefs="DRAWINGS">FIG. 5</figref>, the gas reservoir <b>550</b> is inside of the apparatus <b>500</b>'s enclosure <b>560</b> and is formed by the interior surface of the apparatus <b>500</b>′ enclosure <b>560</b>.

p-0029The first, second, third, and fourth gas pathway portions <b>530</b> are a part of a gas pathway of the apparatus <b>500</b>. One end of the first gas pathway portion <b>530</b><i>a</i>, located at the apparatus <b>500</b>′ inlet side <b>540</b><i>a</i>, is connected to the apparatus <b>500</b>′ enclosure <b>560</b> and the other end of the first gas pathway portion <b>530</b><i>a </i>is connected with the microparticle counter <b>510</b>. One end of the second gas pathway portion <b>530</b><i>b </i>is connected to the microparticle counter <b>510</b>. The other end of the second gas pathway portion <b>530</b><i>b </i>is not connected to any component and is inside of the gas reservoir <b>550</b>. One end of the third gas pathway portion <b>530</b><i>c </i>is not connected to any component and is inside of the gas reservoir <b>550</b>. The other end of the third gas pathway portion <b>530</b><i>c </i>is connected to the vacuum pump <b>520</b>. One end of the fourth gas pathway portion <b>530</b><i>d </i>is connected to the vacuum pump <b>520</b> and the other end of the fourth gas pathway portion <b>530</b><i>d </i>is connected to the apparatus <b>500</b>′ wall at the outlet side <b>540</b><i>b. </i>

p-0030As depicted in <figref idrefs="DRAWINGS">FIG. 5</figref>, the second gas pathway portion <b>530</b><i>b </i>and the third gas pathway portion <b>530</b><i>c </i>are not connected to each other. For example, each of the second and third gas pathway portion <b>530</b><i>cs </i>has a respective end inside of the gas reservoir <b>550</b> that is not connected to any component. According to one embodiment, the gas reservoir <b>550</b> depicted in <figref idrefs="DRAWINGS">FIG. 5</figref>, is air tight and can function even if the vacuum pump <b>520</b> is outside of the apparatus <b>500</b>.

p-0031<figref idrefs="DRAWINGS">FIG. 6</figref> depicts a block diagram of a microparticle measurement apparatus <b>600</b>, according to one embodiment. As depicted in <figref idrefs="DRAWINGS">FIG. 6</figref>, the apparatus <b>600</b> includes a microparticle counter <b>610</b>, a vacuum pump <b>620</b> and enclosure <b>660</b>. The microparticle counter <b>610</b> and the vacuum pump <b>620</b> are inside of the enclosure <b>660</b>. The apparatus <b>600</b> may include one or more external fittings, located at the apparatus <b>600</b>'s enclosure <b>660</b>, for connecting a gas reservoir <b>650</b>, which is outside of the enclosure <b>660</b>.

p-0032One end of the first gas pathway portion <b>630</b><i>a</i>, located at the apparatus <b>600</b>'s inlet side <b>640</b><i>a</i>, is connected to the apparatus <b>600</b>'s enclosure <b>660</b> and the other end of the first gas pathway portion <b>630</b><i>a </i>is connected to the microparticle counter <b>610</b>. One end of the second gas pathway portion <b>630</b><i>b </i>is connected to the microparticle counter <b>610</b> and the other end to the second gas pathway portion <b>630</b><i>b </i>is connected to a first external fitting of the apparatus <b>600</b>. One end of a third gas pathway portion <b>630</b><i>c </i>is connected to a second external fitting of the apparatus <b>600</b>. The other end of the third gas pathway portion <b>630</b><i>c </i>is connected to the vacuum pump <b>620</b>. One end of a fourth gas pathway portion <b>630</b><i>d </i>is connected to the vacuum pump <b>620</b> and the other end of the fourth gas pathway portion <b>630</b><i>d </i>is connected with the apparatus <b>600</b>'s enclosure <b>660</b> at the outlet side <b>640</b><i>b. </i>

p-0033According to one embodiment, a gas reservoir <b>650</b>, which is outside of the apparatus <b>600</b>'s enclosure <b>660</b>, can be coupled with the apparatus <b>600</b> at the first and second external fittings. According to one embodiment, the external gas reservoir <b>650</b> may or may not be an integral part of the apparatus <b>600</b>. As depicted in <figref idrefs="DRAWINGS">FIG. 6</figref>, the gas reservoir <b>650</b> is located at a portion of a gas pathway that is between the microparticle counter <b>610</b> and the vacuum pump <b>620</b>.

p-0034The blocks that represent features in <figref idrefs="DRAWINGS">FIGS. 3-6</figref> can be arranged differently than as illustrated, and can implement additional or fewer features than what are described herein. Further, the features represented by the blocks in <figref idrefs="DRAWINGS">FIGS. 3-6</figref> can be combined in various ways. The apparatuses <b>300</b>-<b>600</b> can be implemented using hardware, hardware and software, hardware and firmware, or a combination thereof.

p-0035According to one embodiment, the gas reservoir serves to increase the capacity of the gas pathway. According to one embodiment, the shape of the gas reservoir is not important.

p-0036<figref idrefs="DRAWINGS">FIG. 7</figref> depicts a gas reservoir, according to one embodiment. According to one embodiment, the gas reservoir <b>710</b> is part of a gas pathway portion <b>720</b>, associated with a microparticle measurement apparatus, and has a larger diameter than the rest of the gas pathway portion <b>720</b>. As depicted in <figref idrefs="DRAWINGS">FIG. 7</figref>, the gas reservoir is located in line with the gas pathway.

p-0037<figref idrefs="DRAWINGS">FIG. 8</figref> depicts a gas reservoir, according to one embodiment. According to one embodiment, the gas reservoir <b>810</b> is a cylindrical shaped component. As depicted in <figref idrefs="DRAWINGS">FIG. 8</figref>, the gas reservoir <b>810</b> is not in line with gas pathway portion <b>820</b> associated with a microparticle measurement apparatus. For example, the gas reservoir <b>810</b> is located at a branch <b>830</b> of the gas pathway portion <b>820</b>.

p-0038<figref idrefs="DRAWINGS">FIG. 9</figref> depicts a gas reservoir, according to one embodiment. According to one embodiment, the gas reservoir <b>910</b> is a long coiled portion <b>930</b> of a gas pathway portion <b>920</b> associated with a microparticle measurement apparatus. According to one embodiment, the long coiled portion <b>930</b> is at least 10 meters (m) long.

p-0039According to one embodiment, a gas reservoir, according to one embodiment, is air tight or partially air tight. A component, such as a vacuum pump or a gas reservoir, that is located outside of the apparatus' enclosure may or may not be a part of the apparatus.

p-0040An apparatus can include one or more external fittings for connecting a vacuum pump or a gas reservoir, which is not inside of the apparatus' enclosure. According to one embodiment, an external gas reservoir or an external vacuum pump may or may not be an integral part of the apparatus. According to one embodiment, the gas reservoir is located at a portion of a gas pathway that is between the microparticle counter and the vacuum pump even when the gas reservoir or the vacuum pump is located outside of the apparatus' enclosure.

p-0041According to one embodiment, a gas pathway portion may go through the wall of a component or may appear to go through the wall of a component. Various embodiments are well suited to implementing a gas pathway portion, for example, using two tubes that are coupled on each side of that component's wall. According to one embodiment, there may be external fittings located at the inlet side or the outlet side of the apparatus at the location of corresponding gas pathway portions.

p-0042According to one embodiment, portions of the gas pathway may be located outside of the apparatus' enclosure. For example, various embodiments are well suited for locating a gas reservoir as depicted in any of <figref idrefs="DRAWINGS">FIG. 7</figref>, <b>8</b>, or <b>9</b> or a vacuum pump outside of the apparatus' enclosure.

p-0043Various embodiments provide for increasing the stability of air pressure using a gas reservoir where the air pressure instability is introduced, for example, at the inlet side. This can level the amount of inflow to an apparatus, according to various embodiments, providing a more accurate dust particle count compared to conventional apparatuses. Various embodiments provide the most accurate measurements when the nozzle's tip is in close proximity with an electronic item's surface that is being measured, for example, with little or no gap between the nozzle's tip and the electronic item's surface. Various embodiments provide for increasing the lifespan of the apparatus due, for example, to reduced fluctuations in the air flow rate to the vacuum pump, reduced load on the vacuum pump, and reduced obstructions of the gas pathway. Various embodiments provide for increased control of the air flow rate and increased control in the production process. For example, the technicians can focus more on other tasks in progress and at the same time, the apparatus does not use or does not require a pressure compensation mechanism, according to one embodiment. For at least this reason, according to various embodiments, the apparatus can be simplified in comparison to conventional apparatus, thus, providing a cost savings.

p-0044The following illustrates a theoretical simulation of a microparticle measurement apparatus, according to various embodiments. Gas, such as air, generally conforms to what is considered to be the gas law as follows: <br /><i>PV=nRT</i>  (eq 1)<br /> where P is pressure of a gas, V is the volume of the gas, R is the gas constant, n is the amount of substance of gas, and T is the temperature of the gas.

p-0045When the temperature is deemed to be fixed, the right-hand side of equation 1 is a constant. <br /><i>PV=C</i>  (eq 2)

p-0046When both sides are differentiated, <br /><i>dP/dt·V+P·dV/dt</i>  (eq 3)<br /><i>dP/dt=−P/V·dV/dt</i>  (eq 4)

p-0047The pressure fluctuation is proportional to PN, according to one embodiment.

p-0048In this illustration of the theoretical simulation of a microparticle measurement apparatus, the microparticle measurement apparatus is assumed to have an air flow rate of 1 cubic feet per minute (cfm). The following shall discuss two postulated cases. The first case involves a conventional microparticle apparatus without a gas reservoir that includes a microparticle counter and a vacuum pump connected by a gas pathway that has a diameter of 1 centimeter (cm) and a length of 5 cm. When separate components are simply connected, this value can be reduced; however, a fairly large value is assumed within the range that can be hypothesized.

p-0049The second case involves a microparticle apparatus that includes a gas reservoir, a microparticle counter and a vacuum pump connected by a gas pathway that has a diameter of 1 cm and a length of 5 cm. When separate components are simply connected, this value can be reduced; however, a fairly large value is assumed within the range that can be hypothesized. In this second case, the gas reservoir is assumed to have a 500 cc capacity.

p-0050The volume of the gas pathway, in the conventional microparticle apparatus without the gas reservoir, is 3.9 cc. In contrast, the volume of the gas pathway, when the apparatus includes a 500 cc gas reservoir, is 503.9 cc.

p-0051Regardless of the value of pressure P, the value of PV is proportional to the reciprocal of the value already obtained. For example, the magnitude of the value for a conventional apparatus without a gas reservoir is approximately 100. In contrast, the magnitude of the value for an apparatus with a gas reservoir, according to various embodiments, has a relationship of approximately 0.8. According to one embodiment, it is possible to restrict momentary fluctuations in air pressure to less than 1 percent. For example, according to one embodiment, it is possible to restrict momentary fluctuations in air pressure to 0.8 percent. When the capacity of the gas reservoir is assumed to be 300 cc, it is possible to restrict momentary fluctuations in air pressure to approximately 1.3 percent.

p-0052The vacuum pump may have to suction surplus gas in proportion to the capacity of the gas reservoir. However, calculations based on the assumption that the capacity of the gas reservoir is 500 cc indicate that it takes approximately 1 second to suction the 500 cc of gas with an air flow rate of 1 cfm. Consequently, the simulation indicates that the impact of possible surplus gas due to a gas reservoir is negligible.

p-0053Although the simulation of an apparatus, according to various embodiments, assumed certain measurements of components, such as certain diameters, lengths, capacities, among other things, various embodiments are well suited for other measurements. Although a simulation of an apparatus, according to various embodiments, assumed a gas reservoir with a capacity of 500 cc, various embodiments are well suited to gas reservoirs with other capacities.

p-0054Although various embodiments have been described in the context of using an apparatus in quality control, an apparatus, according to various embodiments, can be used for other purposes, such as environmental purposes. For example, an apparatus can be used for measuring fibers, such as asbestos. In another example, an apparatus can be used for measuring a level of cleanliness.

p-0055Example embodiments of the subject matter are thus described. Although the subject matter has been described in a language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

p-0056Various embodiments have been described in various combinations and illustrations. However, any two or more embodiments or features may be combined. Further, any embodiment or feature may be used separately from any other embodiment or feature. Phrases, such as “an embodiment,” “one embodiment,” among others, used herein, are not necessarily referring to the same embodiment. Features, structures, or characteristics of any embodiment may be combined in any suitable manner with one or more other features, structures, or characteristics.